sina=(4-2m)/(m+5),cosa=(m-3)/(m+5),a为4项限角,求tana

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sina=(4-2m)/(m+5),cosa=(m-3)/(m+5),a为4项限角,求tana
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sina=(4-2m)/(m+5),cosa=(m-3)/(m+5),a为4项限角,求tana
sina=(4-2m)/(m+5),cosa=(m-3)/(m+5),a为4项限角,求tana

sina=(4-2m)/(m+5),cosa=(m-3)/(m+5),a为4项限角,求tana
sin^2a+cos^2a=1
即:(4-2m)^2/(m+5)^2+(m-3)^2/(m+5)^2=1
(4-2m)^2+(m-3)^2=(m+5)^2
化建得:m(m-8)=0
m=8或0
因为:第四象限,所以sina0
分别代入
m=8 sina=-12/130
m=-0 sina=4/5>0 cosa=-3/5